This is an application for funds to purchase a Becton Dickinson LSRII quadruple laser analytical flow cytometer for use by 15 basic science investigators involved in over 20 NIH-funded projects. This instrument will support a diverse group of research activities, including cancer immunology, stem cell biology, gene therapy, and developmental biology. The instrument will be equipped with a 488 nm argon laser, enabling standard fluorochromes such as fluorescein and phycoerythrin to be detected. It will also have a UV laser, allowing identification of stem cells using the "side population" method of Hoechst dye efflux. Involved investigators studying bone marrow, mammary gland, and hepatic stem cells will utilize this feature. The instrument will also have a helium-neon laser, allowing the detection of additional fluorochromes such as allophycocyanin, which will give added power and flexibility to analyses for all of the investigators, and a violet laser, allowing tracking of cyan fluorescent protein and calcium flux studies. Finally, it will be equipped with an auto sample loader, capable of sampling from 96-well plates, which will assist in accomplishing high throughput screens being pursued by several investigators, as well as ensure the machine is used as efficiently as possible, allowing sufficient running time for all investigators. [unreadable] [unreadable] [unreadable]